The basic idea of a circuit emulation service over packet (CESoP for short) is to establish a channel on a packet-switched network, where time division multiplexing (TDM for short) circuit (such as T1 or E1) transmission is implemented over the channel.
Specifically, a typical application of CESoP service transmission is as follows. A cellular backhaul unit (CBU for short) accesses an E1 service, encapsulates the E1 service according to the CESoP packet format, and transmits the packet to an optical line termination (OLT for short) device over a passive optical network (PON for short). The OLT device parses the CESoP service to obtain the E1 service, puts the E1 service into a synchronous digital hierarchy (SDH for short) frame according to configuration, and transmits the frame by using a synchronous transfer mode-1 (STM-1 for short) interface.
In actual networking, to improve reliability, the OLT device provides two ports, that is, one active port and one standby port. When the active port or the board where the active port resides is faulty, the OLT device automatically switches to the standby port and continues to work.
During CESoP service transmission, a sending device and a receiving device need to configure a media access control (MAC for short) address of the peer end for CESoP service use. For example, in the above typical application, the MAC address of the OLT device needs to be configured on the CBU. When switching from the active port to the standby port, the OLT device usually uses the MAC address of the active port as the current MAC address for CESoP service transmission. This causes a problem that, when the active port is faulty or replaced, if the MAC address of the active port is still used and is configured on the CBU, MAC address conflict may occur, further causing service interruption.